Pre-flare activity of M1.2 flare1,2, 1, 1, 1, 21. Korea Astronomy and Space Science Institute2. Kyung Hee University

ContentsIntroductionDataResultSummaryFuture work

Pre-flareEnhancement before impulsive phase Well defined at the soft X-ray wavelength

Trigger main flare and solar eruption?Independent energy release magnetic reconnection ? Introduction

Relationship with solar activitySimnett, Harrison (1984)CME onset time pre-flare time Ohyama (1997) 1993 C9.7 Pre-flare heating (11 4MK) > plasma ejecta Moon et al. (2004) 2000 X1.8 pre-flare brightenings just before the eruption near the footpoint of the filamentIntroduction

Research of pre-flare using various observations - Multi-wavelength brightenings & reconnection : Harry Warren(1999), Zhang Heng(2000), S.A. Matthews(2003) so on.

They cant show loop structure like reconnection

We report brightening and loop reconnection associated with pre-flare activity using high resolution data.Introduction

Data (1999/1/16 M1.2)Yohkoh SXT 0.25 ~ 4.0kev (360) - 5-6 filter Thin Aluminum Quiet Mode (QT) - Time R ~ 3min Partial Frame Image (PFI) - pixel R : 5 , FOV : 5

Yohkoh BCS (Bragg Crystal Spectrometer) : S XV ~5 GOES 8 X-ray flux curve : 0.54.0, 1.08.0TRACE UV 1600 : Time R = 30s, pixel R = 0.5BBSO Magnetogram

ResultsFlaring time 19:50 ~ 20:02 Pre-flare time 19:46AR 8440( E31N20 )

Pre-flare 19:461.0~8.0A0.5~4.0A

Temperature (GOES) Pre-flare ~ 6MKFlare ~ 16MK

Light curvesGOES : BCS/YohkohFull SunSXT (3min) : TRACE 1600 (30s)Pre-flaring region 132BCSGOES flux TRACESXT

X-ray & UV imagesSize ~ 20 arcsecYohkoh Soft X-rayPixel R = 10 TRACE 1600 Pixel R = 0.5 Foot point BrighteningSigmoid and eruption

Magnetogram (BBSO)

X-ray & UV images

19:39:29 UT19:40:0419:43:2819:45:4819:46:24 19:46:59 aabbaabababba = - b = +123

loop structureTether cuttingMoore & Sterling 2001Van Ballegooijen 1989

Summary

At pre-flare time, there are brightenings in GOES X-ray, SXT partial frames, BCS and TRACE UV 1600A.

TRACE UV images show small-scale sigmoid loops which are co-spatial with SXT brightening foot point on the polarity inversion line.

There was the interaction between sheared loops and then large-sized rising loops were formed.

The evolution of these loops is similar to Moore(1999), Van Balliegooijen (1989) Model.

Our studies imply that the small-scale pre-flare activity be due to magnetic reconnection.

Yohkohs BCS (see Culhane et al. 1991 and Lang et al. 1992for overviews) consists of four channels, covering the resonancelines and principal satellite lines of H-like iron, (Fe xxvi, nominallycovering the wavelength range 1.76361.8044 A); Helikeiron (Fe xxv, 1.82981.8942 A), He-like calcium (Ca xix,3.16313.1912 A), and He-like sulfur (S xv, 5.01605.1143 A).Only the S xv channel covers a low enough energy range to observeemissions from non-flaring active regions routinely, andtherefore our BCS work here is confined to S xv results.